Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 1 | /* |
| 2 | * This is a module which is used for setting the MSS option in TCP packets. |
| 3 | * |
| 4 | * Copyright (C) 2000 Marc Boucher <marc@mbsi.ca> |
Patrick McHardy | f229f6c | 2013-04-06 15:24:29 +0200 | [diff] [blame] | 5 | * Copyright (C) 2007 Patrick McHardy <kaber@trash.net> |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License version 2 as |
| 9 | * published by the Free Software Foundation. |
| 10 | */ |
Jan Engelhardt | 8bee4ba | 2010-03-17 16:04:40 +0100 | [diff] [blame] | 11 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 12 | #include <linux/module.h> |
| 13 | #include <linux/skbuff.h> |
| 14 | #include <linux/ip.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 15 | #include <linux/gfp.h> |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 16 | #include <linux/ipv6.h> |
| 17 | #include <linux/tcp.h> |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 18 | #include <net/dst.h> |
| 19 | #include <net/flow.h> |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 20 | #include <net/ipv6.h> |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 21 | #include <net/route.h> |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 22 | #include <net/tcp.h> |
| 23 | |
| 24 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 25 | #include <linux/netfilter_ipv6/ip6_tables.h> |
| 26 | #include <linux/netfilter/x_tables.h> |
| 27 | #include <linux/netfilter/xt_tcpudp.h> |
| 28 | #include <linux/netfilter/xt_TCPMSS.h> |
| 29 | |
| 30 | MODULE_LICENSE("GPL"); |
| 31 | MODULE_AUTHOR("Marc Boucher <marc@mbsi.ca>"); |
Jan Engelhardt | 2ae15b6 | 2008-01-14 23:42:28 -0800 | [diff] [blame] | 32 | MODULE_DESCRIPTION("Xtables: TCP Maximum Segment Size (MSS) adjustment"); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 33 | MODULE_ALIAS("ipt_TCPMSS"); |
| 34 | MODULE_ALIAS("ip6t_TCPMSS"); |
| 35 | |
| 36 | static inline unsigned int |
| 37 | optlen(const u_int8_t *opt, unsigned int offset) |
| 38 | { |
| 39 | /* Beware zero-length options: make finite progress */ |
| 40 | if (opt[offset] <= TCPOPT_NOP || opt[offset+1] == 0) |
| 41 | return 1; |
| 42 | else |
| 43 | return opt[offset+1]; |
| 44 | } |
| 45 | |
Gao feng | 7722e0d | 2013-09-26 15:00:31 +0800 | [diff] [blame] | 46 | static u_int32_t tcpmss_reverse_mtu(struct net *net, |
| 47 | const struct sk_buff *skb, |
Gao feng | de1389b | 2013-09-26 15:00:30 +0800 | [diff] [blame] | 48 | unsigned int family) |
| 49 | { |
| 50 | struct flowi fl; |
| 51 | const struct nf_afinfo *ai; |
| 52 | struct rtable *rt = NULL; |
| 53 | u_int32_t mtu = ~0U; |
| 54 | |
| 55 | if (family == PF_INET) { |
| 56 | struct flowi4 *fl4 = &fl.u.ip4; |
| 57 | memset(fl4, 0, sizeof(*fl4)); |
| 58 | fl4->daddr = ip_hdr(skb)->saddr; |
| 59 | } else { |
| 60 | struct flowi6 *fl6 = &fl.u.ip6; |
| 61 | |
| 62 | memset(fl6, 0, sizeof(*fl6)); |
| 63 | fl6->daddr = ipv6_hdr(skb)->saddr; |
| 64 | } |
| 65 | rcu_read_lock(); |
| 66 | ai = nf_get_afinfo(family); |
| 67 | if (ai != NULL) |
Gao feng | 7722e0d | 2013-09-26 15:00:31 +0800 | [diff] [blame] | 68 | ai->route(net, (struct dst_entry **)&rt, &fl, false); |
Gao feng | de1389b | 2013-09-26 15:00:30 +0800 | [diff] [blame] | 69 | rcu_read_unlock(); |
| 70 | |
| 71 | if (rt != NULL) { |
| 72 | mtu = dst_mtu(&rt->dst); |
| 73 | dst_release(&rt->dst); |
| 74 | } |
| 75 | return mtu; |
| 76 | } |
| 77 | |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 78 | static int |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 79 | tcpmss_mangle_packet(struct sk_buff *skb, |
Phil Oester | 70d19f8 | 2013-06-12 10:44:51 +0200 | [diff] [blame] | 80 | const struct xt_action_param *par, |
Gao feng | de1389b | 2013-09-26 15:00:30 +0800 | [diff] [blame] | 81 | unsigned int family, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 82 | unsigned int tcphoff, |
| 83 | unsigned int minlen) |
| 84 | { |
Phil Oester | 70d19f8 | 2013-06-12 10:44:51 +0200 | [diff] [blame] | 85 | const struct xt_tcpmss_info *info = par->targinfo; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 86 | struct tcphdr *tcph; |
Pablo Neira Ayuso | 71ffe9c | 2013-07-25 10:37:49 +0200 | [diff] [blame] | 87 | int len, tcp_hdrlen; |
| 88 | unsigned int i; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 89 | __be16 oldval; |
| 90 | u16 newmss; |
| 91 | u8 *opt; |
| 92 | |
Phil Oester | b396966 | 2013-06-12 10:58:20 +0200 | [diff] [blame] | 93 | /* This is a fragment, no TCP header is available */ |
| 94 | if (par->fragoff != 0) |
Phil Oester | 1205e1f | 2013-09-01 08:32:21 -0700 | [diff] [blame] | 95 | return 0; |
Phil Oester | b396966 | 2013-06-12 10:58:20 +0200 | [diff] [blame] | 96 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 97 | if (!skb_make_writable(skb, skb->len)) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 98 | return -1; |
| 99 | |
Pablo Neira Ayuso | 71ffe9c | 2013-07-25 10:37:49 +0200 | [diff] [blame] | 100 | len = skb->len - tcphoff; |
| 101 | if (len < (int)sizeof(struct tcphdr)) |
| 102 | return -1; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 103 | |
Pablo Neira Ayuso | 71ffe9c | 2013-07-25 10:37:49 +0200 | [diff] [blame] | 104 | tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); |
| 105 | tcp_hdrlen = tcph->doff * 4; |
| 106 | |
Eric Dumazet | ced7689 | 2017-04-03 10:55:11 -0700 | [diff] [blame] | 107 | if (len < tcp_hdrlen || tcp_hdrlen < sizeof(struct tcphdr)) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 108 | return -1; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 109 | |
| 110 | if (info->mss == XT_TCPMSS_CLAMP_PMTU) { |
Eric W. Biederman | 686c9b5 | 2015-09-18 14:32:59 -0500 | [diff] [blame] | 111 | struct net *net = par->net; |
Gao feng | 7722e0d | 2013-09-26 15:00:31 +0800 | [diff] [blame] | 112 | unsigned int in_mtu = tcpmss_reverse_mtu(net, skb, family); |
Gao Feng | 50f4c7b | 2016-09-07 10:40:24 +0800 | [diff] [blame] | 113 | unsigned int min_mtu = min(dst_mtu(skb_dst(skb)), in_mtu); |
Gao feng | de1389b | 2013-09-26 15:00:30 +0800 | [diff] [blame] | 114 | |
Gao Feng | 50f4c7b | 2016-09-07 10:40:24 +0800 | [diff] [blame] | 115 | if (min_mtu <= minlen) { |
Joe Perches | e87cc47 | 2012-05-13 21:56:26 +0000 | [diff] [blame] | 116 | net_err_ratelimited("unknown or invalid path-MTU (%u)\n", |
Gao Feng | 50f4c7b | 2016-09-07 10:40:24 +0800 | [diff] [blame] | 117 | min_mtu); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 118 | return -1; |
| 119 | } |
Gao Feng | 50f4c7b | 2016-09-07 10:40:24 +0800 | [diff] [blame] | 120 | newmss = min_mtu - minlen; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 121 | } else |
| 122 | newmss = info->mss; |
| 123 | |
| 124 | opt = (u_int8_t *)tcph; |
Pablo Neira Ayuso | 71ffe9c | 2013-07-25 10:37:49 +0200 | [diff] [blame] | 125 | for (i = sizeof(struct tcphdr); i <= tcp_hdrlen - TCPOLEN_MSS; i += optlen(opt, i)) { |
| 126 | if (opt[i] == TCPOPT_MSS && opt[i+1] == TCPOLEN_MSS) { |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 127 | u_int16_t oldmss; |
| 128 | |
| 129 | oldmss = (opt[i+2] << 8) | opt[i+3]; |
| 130 | |
Benjamin LaHaise | 1700806 | 2007-12-17 22:27:36 -0800 | [diff] [blame] | 131 | /* Never increase MSS, even when setting it, as |
| 132 | * doing so results in problems for hosts that rely |
| 133 | * on MSS being set correctly. |
| 134 | */ |
| 135 | if (oldmss <= newmss) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 136 | return 0; |
| 137 | |
| 138 | opt[i+2] = (newmss & 0xff00) >> 8; |
Jan Engelhardt | 7c4e36b | 2007-07-07 22:19:08 -0700 | [diff] [blame] | 139 | opt[i+3] = newmss & 0x00ff; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 140 | |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 141 | inet_proto_csum_replace2(&tcph->check, skb, |
| 142 | htons(oldmss), htons(newmss), |
Tom Herbert | 4b048d6 | 2015-08-17 13:42:25 -0700 | [diff] [blame] | 143 | false); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 144 | return 0; |
| 145 | } |
| 146 | } |
| 147 | |
Simon Arlott | 10a1993 | 2010-02-02 15:33:38 +0100 | [diff] [blame] | 148 | /* There is data after the header so the option can't be added |
Pablo Neira Ayuso | 71ffe9c | 2013-07-25 10:37:49 +0200 | [diff] [blame] | 149 | * without moving it, and doing so may make the SYN packet |
| 150 | * itself too large. Accept the packet unmodified instead. |
| 151 | */ |
| 152 | if (len > tcp_hdrlen) |
Simon Arlott | 10a1993 | 2010-02-02 15:33:38 +0100 | [diff] [blame] | 153 | return 0; |
| 154 | |
Eric Dumazet | ced7689 | 2017-04-03 10:55:11 -0700 | [diff] [blame] | 155 | /* tcph->doff has 4 bits, do not wrap it to 0 */ |
| 156 | if (tcp_hdrlen >= 15 * 4) |
| 157 | return 0; |
| 158 | |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 159 | /* |
| 160 | * MSS Option not found ?! add it.. |
| 161 | */ |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 162 | if (skb_tailroom(skb) < TCPOLEN_MSS) { |
| 163 | if (pskb_expand_head(skb, 0, |
| 164 | TCPOLEN_MSS - skb_tailroom(skb), |
Herbert Xu | 2ca7b0a | 2007-10-14 00:39:55 -0700 | [diff] [blame] | 165 | GFP_ATOMIC)) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 166 | return -1; |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 167 | tcph = (struct tcphdr *)(skb_network_header(skb) + tcphoff); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 168 | } |
| 169 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 170 | skb_put(skb, TCPOLEN_MSS); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 171 | |
Phil Oester | 70d19f8 | 2013-06-12 10:44:51 +0200 | [diff] [blame] | 172 | /* |
| 173 | * IPv4: RFC 1122 states "If an MSS option is not received at |
| 174 | * connection setup, TCP MUST assume a default send MSS of 536". |
| 175 | * IPv6: RFC 2460 states IPv6 has a minimum MTU of 1280 and a minimum |
| 176 | * length IPv6 header of 60, ergo the default MSS value is 1220 |
| 177 | * Since no MSS was provided, we must use the default values |
Phil Oester | 409b545 | 2013-06-04 05:09:27 +0000 | [diff] [blame] | 178 | */ |
Phil Oester | 70d19f8 | 2013-06-12 10:44:51 +0200 | [diff] [blame] | 179 | if (par->family == NFPROTO_IPV4) |
| 180 | newmss = min(newmss, (u16)536); |
| 181 | else |
| 182 | newmss = min(newmss, (u16)1220); |
Phil Oester | 409b545 | 2013-06-04 05:09:27 +0000 | [diff] [blame] | 183 | |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 184 | opt = (u_int8_t *)tcph + sizeof(struct tcphdr); |
Pablo Neira Ayuso | 71ffe9c | 2013-07-25 10:37:49 +0200 | [diff] [blame] | 185 | memmove(opt + TCPOLEN_MSS, opt, len - sizeof(struct tcphdr)); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 186 | |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 187 | inet_proto_csum_replace2(&tcph->check, skb, |
Tom Herbert | 4b048d6 | 2015-08-17 13:42:25 -0700 | [diff] [blame] | 188 | htons(len), htons(len + TCPOLEN_MSS), true); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 189 | opt[0] = TCPOPT_MSS; |
| 190 | opt[1] = TCPOLEN_MSS; |
| 191 | opt[2] = (newmss & 0xff00) >> 8; |
Jan Engelhardt | 7c4e36b | 2007-07-07 22:19:08 -0700 | [diff] [blame] | 192 | opt[3] = newmss & 0x00ff; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 193 | |
Tom Herbert | 4b048d6 | 2015-08-17 13:42:25 -0700 | [diff] [blame] | 194 | inet_proto_csum_replace4(&tcph->check, skb, 0, *((__be32 *)opt), false); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 195 | |
| 196 | oldval = ((__be16 *)tcph)[6]; |
| 197 | tcph->doff += TCPOLEN_MSS/4; |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 198 | inet_proto_csum_replace2(&tcph->check, skb, |
Tom Herbert | 4b048d6 | 2015-08-17 13:42:25 -0700 | [diff] [blame] | 199 | oldval, ((__be16 *)tcph)[6], false); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 200 | return TCPOLEN_MSS; |
| 201 | } |
| 202 | |
| 203 | static unsigned int |
Jan Engelhardt | 4b560b4 | 2009-07-05 19:43:26 +0200 | [diff] [blame] | 204 | tcpmss_tg4(struct sk_buff *skb, const struct xt_action_param *par) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 205 | { |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 206 | struct iphdr *iph = ip_hdr(skb); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 207 | __be16 newlen; |
| 208 | int ret; |
| 209 | |
Phil Oester | 70d19f8 | 2013-06-12 10:44:51 +0200 | [diff] [blame] | 210 | ret = tcpmss_mangle_packet(skb, par, |
Gao feng | de1389b | 2013-09-26 15:00:30 +0800 | [diff] [blame] | 211 | PF_INET, |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 212 | iph->ihl * 4, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 213 | sizeof(*iph) + sizeof(struct tcphdr)); |
| 214 | if (ret < 0) |
| 215 | return NF_DROP; |
| 216 | if (ret > 0) { |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 217 | iph = ip_hdr(skb); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 218 | newlen = htons(ntohs(iph->tot_len) + ret); |
Patrick McHardy | be0ea7d | 2007-11-30 01:17:11 +1100 | [diff] [blame] | 219 | csum_replace2(&iph->check, iph->tot_len, newlen); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 220 | iph->tot_len = newlen; |
| 221 | } |
| 222 | return XT_CONTINUE; |
| 223 | } |
| 224 | |
Igor Maravić | c0cd115 | 2011-12-12 02:58:24 +0000 | [diff] [blame] | 225 | #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 226 | static unsigned int |
Jan Engelhardt | 4b560b4 | 2009-07-05 19:43:26 +0200 | [diff] [blame] | 227 | tcpmss_tg6(struct sk_buff *skb, const struct xt_action_param *par) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 228 | { |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 229 | struct ipv6hdr *ipv6h = ipv6_hdr(skb); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 230 | u8 nexthdr; |
Eric Dumazet | d6b3347 | 2016-01-15 08:21:32 -0800 | [diff] [blame] | 231 | __be16 frag_off, oldlen, newlen; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 232 | int tcphoff; |
| 233 | int ret; |
| 234 | |
| 235 | nexthdr = ipv6h->nexthdr; |
Jesse Gross | 75f2811 | 2011-11-30 17:05:51 -0800 | [diff] [blame] | 236 | tcphoff = ipv6_skip_exthdr(skb, sizeof(*ipv6h), &nexthdr, &frag_off); |
Patrick McHardy | 9dc0564 | 2007-11-30 23:58:03 +1100 | [diff] [blame] | 237 | if (tcphoff < 0) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 238 | return NF_DROP; |
Phil Oester | 70d19f8 | 2013-06-12 10:44:51 +0200 | [diff] [blame] | 239 | ret = tcpmss_mangle_packet(skb, par, |
Gao feng | de1389b | 2013-09-26 15:00:30 +0800 | [diff] [blame] | 240 | PF_INET6, |
Jan Engelhardt | 37c0838 | 2008-01-31 04:06:10 -0800 | [diff] [blame] | 241 | tcphoff, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 242 | sizeof(*ipv6h) + sizeof(struct tcphdr)); |
| 243 | if (ret < 0) |
| 244 | return NF_DROP; |
| 245 | if (ret > 0) { |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 246 | ipv6h = ipv6_hdr(skb); |
Eric Dumazet | d6b3347 | 2016-01-15 08:21:32 -0800 | [diff] [blame] | 247 | oldlen = ipv6h->payload_len; |
| 248 | newlen = htons(ntohs(oldlen) + ret); |
| 249 | if (skb->ip_summed == CHECKSUM_COMPLETE) |
| 250 | skb->csum = csum_add(csum_sub(skb->csum, oldlen), |
| 251 | newlen); |
| 252 | ipv6h->payload_len = newlen; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 253 | } |
| 254 | return XT_CONTINUE; |
| 255 | } |
| 256 | #endif |
| 257 | |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 258 | /* Must specify -p tcp --syn */ |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 259 | static inline bool find_syn_match(const struct xt_entry_match *m) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 260 | { |
| 261 | const struct xt_tcp *tcpinfo = (const struct xt_tcp *)m->data; |
| 262 | |
| 263 | if (strcmp(m->u.kernel.match->name, "tcp") == 0 && |
Changli Gao | a3433f3 | 2010-06-12 14:01:43 +0000 | [diff] [blame] | 264 | tcpinfo->flg_cmp & TCPHDR_SYN && |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 265 | !(tcpinfo->invflags & XT_TCP_INV_FLAGS)) |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 266 | return true; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 267 | |
Jan Engelhardt | e1931b7 | 2007-07-07 22:16:26 -0700 | [diff] [blame] | 268 | return false; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 269 | } |
| 270 | |
Jan Engelhardt | 135367b | 2010-03-19 17:16:42 +0100 | [diff] [blame] | 271 | static int tcpmss_tg4_check(const struct xt_tgchk_param *par) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 272 | { |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 273 | const struct xt_tcpmss_info *info = par->targinfo; |
| 274 | const struct ipt_entry *e = par->entryinfo; |
Jan Engelhardt | dcea992 | 2010-02-24 18:34:48 +0100 | [diff] [blame] | 275 | const struct xt_entry_match *ematch; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 276 | |
| 277 | if (info->mss == XT_TCPMSS_CLAMP_PMTU && |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 278 | (par->hook_mask & ~((1 << NF_INET_FORWARD) | |
Patrick McHardy | 6e23ae2 | 2007-11-19 18:53:30 -0800 | [diff] [blame] | 279 | (1 << NF_INET_LOCAL_OUT) | |
| 280 | (1 << NF_INET_POST_ROUTING))) != 0) { |
Jan Engelhardt | 8bee4ba | 2010-03-17 16:04:40 +0100 | [diff] [blame] | 281 | pr_info("path-MTU clamping only supported in " |
| 282 | "FORWARD, OUTPUT and POSTROUTING hooks\n"); |
Jan Engelhardt | d6b00a5 | 2010-03-25 16:34:45 +0100 | [diff] [blame] | 283 | return -EINVAL; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 284 | } |
Pablo Neira Ayuso | 55917a2 | 2015-05-14 14:57:23 +0200 | [diff] [blame] | 285 | if (par->nft_compat) |
| 286 | return 0; |
| 287 | |
Jan Engelhardt | dcea992 | 2010-02-24 18:34:48 +0100 | [diff] [blame] | 288 | xt_ematch_foreach(ematch, e) |
| 289 | if (find_syn_match(ematch)) |
Jan Engelhardt | d6b00a5 | 2010-03-25 16:34:45 +0100 | [diff] [blame] | 290 | return 0; |
Jan Engelhardt | 8bee4ba | 2010-03-17 16:04:40 +0100 | [diff] [blame] | 291 | pr_info("Only works on TCP SYN packets\n"); |
Jan Engelhardt | d6b00a5 | 2010-03-25 16:34:45 +0100 | [diff] [blame] | 292 | return -EINVAL; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 293 | } |
| 294 | |
Igor Maravić | c0cd115 | 2011-12-12 02:58:24 +0000 | [diff] [blame] | 295 | #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
Jan Engelhardt | 135367b | 2010-03-19 17:16:42 +0100 | [diff] [blame] | 296 | static int tcpmss_tg6_check(const struct xt_tgchk_param *par) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 297 | { |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 298 | const struct xt_tcpmss_info *info = par->targinfo; |
| 299 | const struct ip6t_entry *e = par->entryinfo; |
Jan Engelhardt | dcea992 | 2010-02-24 18:34:48 +0100 | [diff] [blame] | 300 | const struct xt_entry_match *ematch; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 301 | |
| 302 | if (info->mss == XT_TCPMSS_CLAMP_PMTU && |
Jan Engelhardt | af5d6dc | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 303 | (par->hook_mask & ~((1 << NF_INET_FORWARD) | |
Patrick McHardy | 6e23ae2 | 2007-11-19 18:53:30 -0800 | [diff] [blame] | 304 | (1 << NF_INET_LOCAL_OUT) | |
| 305 | (1 << NF_INET_POST_ROUTING))) != 0) { |
Jan Engelhardt | 8bee4ba | 2010-03-17 16:04:40 +0100 | [diff] [blame] | 306 | pr_info("path-MTU clamping only supported in " |
| 307 | "FORWARD, OUTPUT and POSTROUTING hooks\n"); |
Jan Engelhardt | d6b00a5 | 2010-03-25 16:34:45 +0100 | [diff] [blame] | 308 | return -EINVAL; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 309 | } |
Pablo Neira Ayuso | 55917a2 | 2015-05-14 14:57:23 +0200 | [diff] [blame] | 310 | if (par->nft_compat) |
| 311 | return 0; |
| 312 | |
Jan Engelhardt | dcea992 | 2010-02-24 18:34:48 +0100 | [diff] [blame] | 313 | xt_ematch_foreach(ematch, e) |
| 314 | if (find_syn_match(ematch)) |
Jan Engelhardt | d6b00a5 | 2010-03-25 16:34:45 +0100 | [diff] [blame] | 315 | return 0; |
Jan Engelhardt | 8bee4ba | 2010-03-17 16:04:40 +0100 | [diff] [blame] | 316 | pr_info("Only works on TCP SYN packets\n"); |
Jan Engelhardt | d6b00a5 | 2010-03-25 16:34:45 +0100 | [diff] [blame] | 317 | return -EINVAL; |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 318 | } |
| 319 | #endif |
| 320 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 321 | static struct xt_target tcpmss_tg_reg[] __read_mostly = { |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 322 | { |
Jan Engelhardt | ee999d8 | 2008-10-08 11:35:01 +0200 | [diff] [blame] | 323 | .family = NFPROTO_IPV4, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 324 | .name = "TCPMSS", |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 325 | .checkentry = tcpmss_tg4_check, |
| 326 | .target = tcpmss_tg4, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 327 | .targetsize = sizeof(struct xt_tcpmss_info), |
| 328 | .proto = IPPROTO_TCP, |
| 329 | .me = THIS_MODULE, |
| 330 | }, |
Igor Maravić | c0cd115 | 2011-12-12 02:58:24 +0000 | [diff] [blame] | 331 | #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 332 | { |
Jan Engelhardt | ee999d8 | 2008-10-08 11:35:01 +0200 | [diff] [blame] | 333 | .family = NFPROTO_IPV6, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 334 | .name = "TCPMSS", |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 335 | .checkentry = tcpmss_tg6_check, |
| 336 | .target = tcpmss_tg6, |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 337 | .targetsize = sizeof(struct xt_tcpmss_info), |
| 338 | .proto = IPPROTO_TCP, |
| 339 | .me = THIS_MODULE, |
| 340 | }, |
| 341 | #endif |
| 342 | }; |
| 343 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 344 | static int __init tcpmss_tg_init(void) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 345 | { |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 346 | return xt_register_targets(tcpmss_tg_reg, ARRAY_SIZE(tcpmss_tg_reg)); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 347 | } |
| 348 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 349 | static void __exit tcpmss_tg_exit(void) |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 350 | { |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 351 | xt_unregister_targets(tcpmss_tg_reg, ARRAY_SIZE(tcpmss_tg_reg)); |
Patrick McHardy | cdd289a | 2007-02-07 15:09:46 -0800 | [diff] [blame] | 352 | } |
| 353 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 354 | module_init(tcpmss_tg_init); |
| 355 | module_exit(tcpmss_tg_exit); |